Flap switch for conveyor system



Feb. 23, 1965' Filed June 8. 1961 PRIOR ART OPERATION G. BURKHARDT ETAL FLAP swI'rcH FOR CONVEYOR SYSTEM 3 Sheets-Sheet 1 Fig. Ia

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INVENTORS Gisbert Burkhardta Max Peek Y r '11 I ATTORNEY 23, 1965 s. BURKHARDT EI'AL 3,170,636

FLAP SWITCH FQR CONVEYOR SYSTEM Filed June 8. 1961 3 Sheets-Sheet 2 f3 I I 7 4 l I l I I I i I I I l l l l l I s 1 0 s 4' f F1 .217 15 v g a -17 l INVENTCRS b Gisbert Burkhardta i Max Peek av 9 ATTORNEY Feb. 23, 1965 BURKHARDT E 3,170,686

FLAP SWITCH "FOR CONVEYOR SYSTEM Filed June 8. 1961 s Sheets-Sheet s ATTORNEY United States Patent 3,170,686 FLAP SWITCH FOR CONVEYOR SYSTEM Gisbert Burlkhardt, Konstanz, and Max Peek, Darmstadt, Germany, assignors to Telefunken Patentverwertungs G.m.b.H., Ulm (Danube), Germany Filed June 8, 1961, Ser. No. 115,784 Claims priority, application Gtserma'ny, June 15, 1960,

T 3 Claims. (Cl. 271-64) storing devices and may be rendered effective by means of mechanical or optical feeler members as a function of the course of the shipments in the conveyor system.

p In order to achieve a high conveying density, the transfer or operating time should be as short as possible in such switches and this is accomplished by an appropriate design of the flap switch and its drive. However, there are limitations since for constructional reasons, the moment of inertia of the flap may not be decreased as desired, and wear resistance and noise development are factors to be taken into consideration. Under certain conditions, a transfer time of about 0.02 second, is achievable at present.

In known flap switch arrangements or assemblies, the switch operating signal for the next shipment is made effective in each case when the shipment has'left the path selecting zone or effective range of the front edge of the flap, i.e., when the shipment has passed through the assembly to such a point that the distance between the front edge of the shipment and the front edge of the flap switch has become equal to or greater than the length of the shipment. Therefore, with any given conveying speed, the permissible minimum distance between shipments is determined by the transfer time of the flap switch. The result of this is that, if a certain conveying speed is exceeded, the distances between shipments must also be increased to such an extent that a substantial increase of the conveying density is no longer possible. These interrelations will be illustrated in greater detail below with reference to the drawing.

With these defects of the prior 'art in mind, it is a main object of the present invention drastically to decrease the distance required between shipments in a device of the character described.

Another object of the invention is to provide a simple yet exceedingly effective flap switch arrangement.

A further object is to provide a flap switch which will act gently on the shipments or articles and not tear them.

The present invention provides a method of controlling a flap switch of the type described which to a largeextent obviates the disadvantageous effect of the transfer time of the flap upon the achievable conveying density. This makes itpossible to keep the distance between shipments very small even at high conveying speeds, therebyresulting in a substantial increase in the conveying density. The

above, is done in such a way that the switch operating signal forthe next shipment is made effective after the front .edgevof a preceding shipment has passed the front edge of the flap switch, and the distance between the frontedge of the shipment and the front edge of the flap switch is still small as compared with the length of the shipment. In practice, the operating signal for the next shipment is in general made effective when the distance between the front edge of the shipment currently in the switch and the front edge of the flap switch is not yet larger than about 30 to 70% of the length of the shipment;

The invention is based on the realization that, contrary to the hitherto usual procedure, the flap switch may be reversed while the shipment is still passing its front edge, as long as the switch is structurally designed in such a way that the flap does not impede, in any of its terminal positions, the complete passage of a shipment which is still passing the front edge of the flap. For this purpose, a flap switch in accordance with the present invention is designed in such a way that the flap in its terminal positions, leaves a gap or clearance open along the lateral limits of the conveying path, the gap width being at least equal to the largest possible thickness of the shipments.

It is, furthermore, advantageous according to the invention for the flap to be rounded off at its front edge in a manner known per se and for the height of the front edge to be so great as to cover at least a medium range of envelopes, as well as a range which will cover the windows which are at timesfitted on envelopes.

If the feeding of the shipments to the switch is done by pairs of rollers, the distance of the center of rotation of the flap from the center of the lastconveyor roller is little greater than the sum of the radius of this roller and the distance from the center of rotation of the flap to its front edge. A switch meeting this condition is already known per. se.

Additional objects and advantages of the present invention will become apparent upon consideration of the following description when taken in conjunction with the accompanying drawings in which:

FIGURES la and lb are operating diagrams of the prior art methods for controlling a flap switc I FIGURES 2a and 2b are similar diagrams illustrating the methodaccordi'ng to the invention. 7

FIGURE 3 is a diagrammatic View of a flap switch suitable for control in the sense of the invention.

FIGURE 4 is a view similar to FIGURE 3 but illustrating another embodiment of the switch assembly.

FIGURE 5 is a plan of the front of an envelope.

To facilitate a better understanding of the invention for controlling a flap switch the conventional method with reference to FIGURES 1a and 1b will be considered first.

The heavy line of FIGURE 1a shows, in the form of an operating diagram, the position of the flap switch as a function of the position of the front edge of a shipment or article A passing through the switch or through the conveying path connected with the switch. The abscissa corresponds to the direction of movement and to the path s of the front edge, While the ordinate indicates the lateral deflection d of the flap switch. Thepossible terminal positions of the flap are designated by d+ and a'--. The switch is assumed to have a rest position and an operating position, Where d+ is the rest position. The point along the path s of the shipment where the front edge of the flap switch is disposed has been designated on the abscissa as s In FIGURE 1b, too, the abscissa corresponds to the path s of the front edge of a shipment. The two FIG- URES 1a and 1b arec'oordinated with 'one another with The ordinate of FIGURE 15 Since a.

3 enter the switch, and, on the basis of the direction of their destination, shipment A requires the switch position d+, shipment B the switch position d, and shipment C again the position 11+. The flap switch is, therefore, in position d+ when the front edge of shipment A has reached point s just before the point s of the front edge of the flap switch (instant 11). Now, in the known switch controls the switch operating signal for the next following shipment B is made eifective when the rear edge of the preceding shipment A has already left the effective range of the front edge of the flap (point s Thus, this occurs when the distance s s between the front edge of the shipment and the front edge of the flap switch is equal to or larger than the length e of the shipment. This is the case at the instant t Now the switch operating signal for shipment B is made effective, so that the flap switch pivots into the position d during a time I 4 in which shipment A moves on to s Only when this position has been attained, may the front edge of the following shipment B be moved to S; as shown. The same is true analogously for the start of the return of the flap switch into position d-lwhen shipment A is at .9 and shipment B is at s (instant t Thus, in this kind of switch control, a relatively large mutual distance between the shipments is necessary, due to the influence of the transfer time (e.g., t t

FIGURES 2a and 2b refer to the method according to the present invention for controlling a flap switch. The illustrations are similar to those of FIGURES la and 1b, and the meaning of the individual coordinates is the same and need not be repeated here. The point at which the front edge of the flap switch is located, is again designated by s likewise the speed at which the shipments pass through the switches is the same.

Assume that shipments A, B, and C successively enter the switch whose control is shown in FIGURES 2a and 2b, the directions of destination of these shipments requiring the same switch positions as in the previously discussed case. Thus, in this case, too, the flap switch is in position d-lwhen shipment A at instant t has reached s just in front of the switch flap (point s In the method of the present invention, however, the switch operating signal for the next shipment B is made effective when the distance between the front edge of shipment A currently in the switch and the front edge of the flap switch, thus the distance s '-s is still small compared to the length of the shipment (instant t In other words, while a large part of shipment A is still in the effective range of the front edge of the switch flap, the signal for the next shipment B may be given. The flap switch now pivots into position d during the time t 't during which time shipment A moves on to s and shipment B to s The same is true for the initiation of the return of the flap switch to position d+, when at instant t shipment A is at s and shipment B at s 7 It may be seen from FIGURES 2aand 2b that the distances between the individual shipments may be substantially smaller than heretofore, without regard to the transfer time t t of the flap switch, which time has not changed. The distances may be' so small that the rear edge of the previous shipment and the front edge of the following shipment are just slightly spaced so they do not touch. In this way, the inventionmakes possible an increase in the conveying density without a further decrease of the transfer time of the flap switch.

FIGURE 3 diagrammatically shows an embodiment of a switch. In front of the switch there is a pair of conveyor rollers 1 and 2, driven in thedirection of the arrows, which are adjacent limiting walls 3 and 4. The flap .is pivotable on its axis 6. It may be actuated, for example, by a rotary magnet (not shown). The flap may assume either the position shown by the continuous line, corresponding to position d+ of FIGURE 2a, or the position shown by the dotted line, corresponding to position d. The front edge of the flap is designated 5 The distance of the axis of rotation of the flap from the axis of the conveyor roller 1 or 2 is, in a manner known per se, somewhat larger than the sum of the radius of the roller and the distance of the axis of the flap 5 from its front edge 5'. Along arrow s, indicating the path of the shipments, the point s of the front edge 5' is indicated, corresponding to FIGURE 2a. When the flap 5 is in the position d+ shown in continuous line, the shipments are directed between lateral limiting walls 7 and 8 to a pair of rollers 9, 10, and from there into a branching off conveying path. When the flap 5 assumes the position d-, the shipments are guided between limiting walls 11 and 12 to a pair of rollers 13, 14, from which they are fed to a further conveying path.

As shown in FIGURE 4, instead of outer limiting walls 3 and 11, conveyor belts 8 and 11' may be used which are disposed in recessed tracks in rollers 2', l0 and 1, 13, respectively.

An essential characteristic of this switch is that the flap 5, in its terminal positions d+ and d, still leaves a gap or clearance open for limiting the lateral dimensions of the conveying path, which gap is adjusted to the largest possible thickness of the shipments. The lateral limitations are understood to mean, for example, the walls 8 and 11, the rollers'l and 2, or the conveyor belts 8' and 11'. It thus becomes possible to make the switch operating signal for the next shipment elfective at an instant ,t (FIGURES 2a and 2b) at which time the previous shipment is still in the range of the front edge 5' of the switch iiap 5. Due to the gap mentioned, the complete passage of this shipment through the assembly is not impeded. Also, the rear end of a shipment that has run to s (FIG- URES 2a, 2b; instant t is not clamped in the assembly, for example between fiap 5 and wall 11.

Furthermore, if postal shipments, such as letters and the like, are concerned, the flap 5 is preferably designed in such a way that its front edge 5 is rounded off as known per se. Moreover, the height of this front edge is chosen so large as to cover at least a medium range a of envelopes and a range b, in which windows may be fitted on envelopes.

With reference to FIGURES, showing an envelope 15, these ranges will be illustrated in more detail. On this envelope, a window opening 17 is illustrated on the front side and the glue flaps of the envelope on the back side. The glue flaps of the window as well as the glue flaps on the back are frequently defectively made. A sharp flap tongue would get caught in defectively made glue flaps, damaging the letters. Moreover, a flap tongue of short height would hook itself fast in the envelope, for example, in printed matter where the flap is inserted into the envelope. In FIGURE 5, the height of the window openings is indicated by b, while a indicates a medium range on the envelope wherein the glue flaps on the back meet. If the front edge of the flap covers these ranges, it can slide over the glue flaps, over the inserted parts in printed matter, and over windows of envelopes without damaging them. Since the flap is rounded off at its front edge, the envelopes are additionally protected.

It will be understood that the above description of the present invention is susceptible to various modifications, changes, and adaptations, and the same are intended to be comprehended within the meaning and range of equiv- .alents of the appended claims.

What is claimed is:

l. A conveying process for directing flat articles along one of a plurality of paths, comprising the steps of: feeding the articles to a path selecting zone with the distance between adjacent articles being not more than 30 to 70% of the length of the articles so that prior to a first article leaving said zone, a second article enters said zone; detecting the second article while the first article is in said zone; and directing the second article entering said zone in said zone.

2. A method of controlling a flap switch in conveyor systems for fiat shipments transported in upright position, comprising the steps of: i I

feeding a first shipment to the flap switch;

detecting a second shipment while said first shipment is in the flap switch; and conditioning the flap switch to assume a position responsive to the detection of said second shipment while said first shipment is still in the flap switch.-

3. A method of controlling a flap switch in conveyor systems for flat shipments transported in upright position, comprising the steps of:

feeding a first shipment to the flap switch;

detecting a second shipment while said first shipment is in the flap switch; and conditioning the flap switch to assume a position reafter the front edge of the first shipment has passed 7 the front edge of the flap switch and when the dis-1 tance between the front edge of thefirst shipment which is in the flap switch and the front edge ofthe; flap switch is not yet larger than about 30 to 701% of the lengthof the shipment;

References Cited in the file of this patent UNITED STATES PATENTS 1,825,217 Tufts et a1. Sept. 29, 1951 1,850,932 Holmes Mar. 22, 1932 2,294,649 Baker Sept. 1, 1942 2,526,916 Turrall 061. 24, 1950 2,563,492 Turrallet a1. Aug. 7, 1951 FOREIGN PATENTS 1,025,484

France Apr. 15, 1953 

2. A METHOD OF CONTROLLING A FLAP SWITCH IN CONVEYOR SYSTEMS FOR FLAT SHIPMENTS TRANSPORTED IN UPRIGHT POSITION, COMPRISING THE STEPS OF: FEEDING A FIRST SHIPMENT TO THE FLAP SWITCH; DETECTING A SECOND SHIPMENT WHILE SAID FIRST SHIPMENT IS IN THE FLAP SWITCH; AND CONDITIONING THE FLAP SWITCH TO ASSUME A POSITION RESPONSIVE TO THE DETECTION OF SAID SECOND SHIPMENT WHILE SAID FIRST SHIPMENT IS STILL IN THE FLAP SWITCH. 